The example that you are using (which is part of the toolkit's shipping examples) don't use the AI Microphone task as they were written before the AI Microphone task was integrated into the DAQmx driver. The AI Microphone Task carries out a lot of the configuration behind the scenes, generally making it easier to use. One example that does use it is Cont Acq Snd Pressure Samples-Int Clk.vi.
The other examples that use AI Voltage don't necessarily have a sensitivity setting. The sensitivity setting is mainly used to scale the voltage to your desired units. This can be easily seen by looking at the example: SVXMPL_Sound Level Meter (DAQmx).vi. In this example you will see the SVL Scale Voltage to EU.vi that uses the sensitivity setting to convert voltage to engineering units. I believe that is basically the same operation that the AI Microphone VI is using behind the scenes. The SVXMPL_WAV Recorder (DAQmx) example is not displaying the data in engineering units because it is just working with a waveform and writing it to a file. So there is no conversion being done to engineering units and hence no sensitivity setting to change.
